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Related papers: Two-loop QCD helicity amplitudes for massless quar…

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We present the one-loop QCD amplitudes for two external massless quarks and three external gluons ($\bar{q}qggg$). This completes the set of one-loop amplitudes needed for the next-to-leading-order corrections to three-jet production at…

High Energy Physics - Phenomenology · Physics 2010-11-15 Z. Bern , L. Dixon , D. A. Kosower

We provide two two-loop amplitudes relevant for precision Higgs physics. The first is the two-loop amplitude for Higgs boson production through gluon fusion with exact dependence on the top quark mass up to squared order in the dimensional…

High Energy Physics - Phenomenology · Physics 2020-08-26 Charalampos Anastasiou , Nicolas Deutschmann , Armin Schweitzer

Inelastic QED processes, the cross sections of which do not drop with increasing energy, play an important role at high-energy colliders. Such reactions have the form of two-jet processes with the exchange of a virtual photon in the…

High Energy Physics - Phenomenology · Physics 2011-09-13 C. Carimalo , A. Schiller , V. G. Serbo

We detail the calculation of two-loop all-plus helicity amplitudes for pure Yang-Mills theory. The four dimensional unitarity methods and augmented recursion techniques we have developed, together with a knowledge of the singular structure…

High Energy Physics - Theory · Physics 2017-12-27 David C. Dunbar , John H. Godwin , Guy R. Jehu , Warren B. Perkins

We present a definition of the four-dimensional helicity (FDH) regularization scheme valid for two or more loops. This scheme was previously defined and utilized at one loop. It amounts to a variation on the standard 't Hooft-Veltman scheme…

High Energy Physics - Phenomenology · Physics 2010-11-15 Z. Bern , A. De Freitas , L. Dixon , H. L. Wong

We present an analytical calculation of the two-loop QCD corrections to the electromagnetic form factor of heavy quarks. The two-loop contributions to the form factor are reduced to linear combinations of master integrals, which are…

High Energy Physics - Phenomenology · Physics 2009-07-29 J. Gluza , A. Mitov , S. Moch , T. Riemann

We combine the six-dimensional helicity formalism of Cheung and O'Connell with D-dimensional generalized unitarity to obtain a new formalism for computing one-loop amplitudes in dimensionally regularized QCD. With this procedure, we…

High Energy Physics - Phenomenology · Physics 2013-05-29 Scott Davies

We study the factorisation properties of one-loop scattering amplitudes in the triple collinear limit and extract the universal splitting amplitudes for processes initiated by a gluon. The splitting amplitudes are derived from the analytic…

High Energy Physics - Phenomenology · Physics 2015-07-20 Simon Badger , Francesco Buciuni , Tiziano Peraro

Recent progress in our understanding of infrared singularities of multi-parton amplitudes has shown that the simplest form of Regge factorization for high-energy gauge-theory amplitudes fails starting at next-to-next-to-leading logarithmic…

High Energy Physics - Phenomenology · Physics 2015-06-17 Vittorio Del Duca , Giulio Falcioni , Lorenzo Magnea , Leonardo Vernazza

The production of a Higgs boson in association with a top-antitop quark pair ($t\bar{t}H$) holds significant importance in directly probing the top-quark Yukawa coupling, which is related to various fundamental questions in high energy…

High Energy Physics - Phenomenology · Physics 2024-02-02 Guoxing Wang , Tianya Xia , Li Lin Yang , Xiaoping Ye

Splitting amplitudes are universal functions governing the collinear behavior of scattering amplitudes for massless particles. We compute the two-loop g -> gg splitting amplitudes in QCD, N=1, and N=4 super-Yang-Mills theories, which…

High Energy Physics - Phenomenology · Physics 2010-03-25 Zvi Bern , Lance J. Dixon , David A. Kosower

In this paper we consider the matching coefficients up to two loops between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) for the vector, axial-vector, scalar and pseudo-scalar currents. The structure of the effective theory…

High Energy Physics - Phenomenology · Physics 2009-11-11 B. A. Kniehl , A. Onishchenko , J. H. Piclum , M. Steinhauser

By taking the high-energy limit of the two-loop amplitudes for parton-parton scattering, we have tested the validity of Fadin-Lipatov's ansatz for parton-parton scattering in the high-energy limit. As expected, we have found that it holds…

High Energy Physics - Phenomenology · Physics 2010-02-03 Vittorio Del Duca , E. W. N. Glover

We compute the one-loop corrections to \tth up to order $\mathcal{O}(\epsilon^2)$ in the dimensional regularization parameter. We apply the projector method to compute polarized amplitudes, which generalize massless helicity amplitudes to…

High Energy Physics - Phenomenology · Physics 2023-12-18 Federico Buccioni , Philipp Alexander Kreer , Xiao Liu , Lorenzo Tancredi

I discuss the recent advances in the computation of two-loop scattering amplitudes for five-particle processes. The latter are fundamental ingredients to obtain predictions at the next-to-next-to-leading order (NNLO) in QCD for many…

High Energy Physics - Phenomenology · Physics 2023-10-09 Simone Zoia

We introduce a formalism for describing four-dimensional scattering amplitudes for particles of any mass and spin. This naturally extends the familiar spinor-helicity formalism for massless particles to one where these variables carry an…

High Energy Physics - Theory · Physics 2021-11-02 Nima Arkani-Hamed , Tzu-Chen Huang , Yu-tin Huang

Two-quark--two-antiquark systems with four different quark flavors are considered in the framework of two-dimensional QCD, in the light-cone gauge, at leading orders of the $1/N_c^{}$ expansion. Introducing basis functions with…

High Energy Physics - Phenomenology · Physics 2025-09-22 Hagop Sazdjian

Using the helicity formalism, we compute the contribution of a quark-antiquark pair to the tree-level multigluon amplitudes in the high-energy limit. The $\bar{q}\, q$-pair production is absent in the leading-log formalism, but contributes…

High Energy Physics - Phenomenology · Physics 2008-11-26 Vittorio Del Duca

We find that scattering amplitudes in massive scalar QCD can manifest the duality between color and kinematics at loop-level. Specifically we construct the one-loop integrands for four-point scattering between two distinct massive scalars,…

High Energy Physics - Theory · Physics 2021-02-10 John Joseph M. Carrasco , Ingrid A. Vazquez-Holm

We compute the ${\cal O}(\alpha_s^3)$ virtual QCD corrections to the $\gamma^*\to q\bar q g$ matrix element arising from the interference of the two-loop with the tree-level amplitude and from the self-interference of the one-loop…

High Energy Physics - Phenomenology · Physics 2010-04-06 L. W. Garland , T. Gehrmann , E. W. N. Glover , A. Koukoutsakis , E. Remiddi